During Phase 1: The Summoning chapter we will be tasked with going inside a closet or a store room. That is located under the main 2F staircase. We can unlock the door to this closet or store room by collecting the (Engraved Key). Once inside you will notice that the room is actually quite small. It also seems to feature a creepy mummy figure.
However, at this point we will need to ‘Use the panel to open the 2F Gate’. The way to do this is to solve a quick puzzle. This puzzle will involve numbers and a switch panel. Solving this puzzle will unlock the 2F staircase gate. So how do we solve it then? Simple really..
When you collect the (Engraved Key) you will also, automatically, receive the ‘Information Plaque’. The answer to the puzzle resides on it. Super useful. Why? well if you read it the plaque will mention ‘Ensure the numbers total up to 13’. This is basically the answer to the puzzle. The number 13.
Turn and use the panel and make sure you reach that target number. For those that might still be having difficulty then use the following numbers; 4, 5, 1, 0, 3. If you add all of those numbers together you will reach your target number.
Now the 2F staircase gate will unlock and we can proceed with the main story.